Communication systems, such as two-way cable television systems, typically process signals in both the forward, or downstream, direction and the reverse, or upstream, direction. These signals may travel long distances and, as a result, distribution amplifiers are typically employed to amplify the signal levels of the forward and reverse signals.
Thermal circuits are often employed to detect the temperature within the amplifier. As the temperature within the amplifier rises, a variable attenuator, such as a Bode circuit, is adjusted to boost the gain of the amplifier. This compensates for the decrease in gain that is a normal consequence of higher temperatures. Thermal circuits, however, are relatively imprecise and may not be able to compensate for other causes of gain variation. As a result, some amplifiers alternatively use automatic gain control (AGC) circuits. Although AGC circuits provide better performance, they typically use a larger number of components, require more space within an amplifier, and cost more than conventional thermal circuits.
Thus, what is needed is a more flexible way to provide signal level control in an amplifier for a communication system.